Walls can’t talk, but scientists can now read stories written in their subatomic particles. And that could make it harder to store radioactive material in secret. Authorities could use this technique to retrace where a dirty bomb was stored before detonation to figure out who built it, says Eric Lukosi, a nuclear engineer at UT who was not involved in the work. “This is still very early in its development,” Lukosi says, “but it’s an interesting approach.”